In commenting on this thread http://boards.straightdope.com/sdmb/showthread.php?threadid=111012 , I referred to what I called “Oirish”. I said it is an occult dialect found only in American and British films. It bears little relation to any dialect or accent actually existing in Ireland.
This “Irish” dialect or accent has grown its own vocabulary. In particular, it has developed a word “begorrah”, which is routinely used when imitating Irish people.
In nearly fifty years in Ireland, I have never heard an Irish person use “Begorrah” in normal conversation. They only use it to poke fun at stage Irish or Oirish images of Ireland. They use many parallel abbreviations or distortions of “by god”, but not that particular formation.
Where did this word come from, and why is it seen as the typical Irish exclamation?
I can’t find any mention of “begorrah”, but P.W. Joyce’s English As We Speak It In Ireland does mention “begor” as a swear word actually used in Ireland (keep in mind he was writing almost 100 years ago).
Joyce considered it just a sanitisation of “By God”. I wouldn’t put a great deal of trust in his etymologies (he was a hobbyist, not a scholar, in this field) but this one strikes me as likelier than not.
I heard a farmer say “begorra begod” in Co. Carlow, which might tally with Joyce’s interpretation. However, I’ve only heard it once in 7 years living here, and for all I know he could have been taking the piss out of the stereotype, though I got the impression from context that he wasn’t.